Top management support is a key recurrent factor critical for effective information systems (IS) implementation. However, the role of top management support may not be as critical as external IS expertise, in the form of consultants and vendors, in small business IS implementation due to the unique characteristics of small businesses. This paper describes an empirical study of the relative importance of top management support and external IS expertise on IS effectiveness in 114 small businesses. Partial least squares (PLS) was used for statistical testing. The results show that top management support is not as important as effective external IS expertise in small business IS implementation. While top management support is essential for IS effectiveness, high quality external IS expertise is even more critical for small businesses operating in an environment of resource poverty. These findings call for more research efforts to be directed at selecting and engaging high quality external IS expertise for IS implementation in small businesses.